Histamine transport has been characterized in cultured astroglial cells of rat brain. The kinetics of [3H]-histamine uptake yielded a Km of 0.19 +/- 0.03 microM and a Vmax of 3.12 +/- 0.75 pmol X mg protein-1 X min-1. Transport system revealed high affinity for histamine and an approximately ten times higher capacity than that shown in cultured glial cells of chick embryonic brain. Ouabain which interferes with utilization of ATP to generate ion gradients, and the replacement of Na+ with choline inhibited the initial rate of uptake showing a strong Na(+)-dependency and suggesting the presence of a tightly coupled sodium/histamine symporter. Dissipation of K(+)-gradient (in > out) by high K+ or by K(+)-channel blockers, BaCl2, (100 microM), quinine (100 microM) or Sparteine (20 microM) produced also remarkable inhibitions in the uptake of [3H]-histamine. Impromidine, a structural histamine-analogue could inhibit the uptake non-competitively in a range of concentrations of 1 to 10 microM with a Ki value of 2.8 microM, indicating the specificity of the uptake. [3H]histamine uptake measurements carried out by using a suspension of dissociated hypothalamic cells, of rat brain showed a strong gliotoxin-sensitivity and yielded a Km of 0.33 +/- 0.08 microM; and a Vmax of 2.65 +/- 0.35 pmoles x mg protein-1 x min-1. The uptake could be reversed by incubating the cells in histamine-free Krebs medium. The [3H]histamine efflux was sensitive to Na+ omission, ouabain treatment and high K+ or K+ channel blockers, resulting in marked elevations in the efflux.(ABSTRACT TRUNCATED AT 250 WORDS)
The role of Vitamin A in different physiological functions among different species is well known (De Luca, 1978; Wolf, 1984). However, its role in reproduction in general and in embryo production and viability in particular needs further investigation especially in laboratory animals. Very limited work can be found in this regard (NRC, 1978; Chew and Archer, 1983; Kormann a n d Schlachter, 1984; Pusztai et al., 1989; Kormann et al., 1988), which deals with the requirements, dose and effects of Vitamin A o n reproduction performance, neonatal survival and growth of some laboratory species. Our work was directed toward the effect of Vitamin A on female outbred mice receiving commercial diet and injected with an extra NRC recommended dose of Vitamin A o n the number and quality of embryos produced. A total of 804, 7-8 week old outbred female NMRI (Lati, Godollo) mice were used in this study during winter and early spring. Animals were housed in a ventillated room of 24OC, 50% relative humidity and provided with 14 h light daily. Water and food was provided ad libitum. The animals were divided randomly into treated (400) mice or control (404) mice. Treated animals were injected intraperitoneally with 250 I.U. of Vitamin A (A vitamin olajos injekci6, Egis, Budapest), dissolved in 0.1 ml of paraffin or sunflower oil, twice within 1 0 days (NRC, 1978). Control groups were injected with the vehicle only. Animals assigned for superovulation were injected with 7.5 I.U. of PMSG (Folligon, Intervet) followed by 7.5 I.U. of HCG (Choriogonin, KGY, Budapest) 48 h later. Normal induction of ovulation was conducted with 1 I.U. of PMSG followed by 1 I.U. of HCG 48 h later. Each female was placed together with a proven fertile male from the same strain and mating was confirmed next morning by the presence of vaginal plug (designated day 1 ) . Zygotes, morulae a n d blastocysts were flushed on days 1 , 3 und 4 respectively from the oviducts and the uterine horns using sterile drops of Dulbecco's PBS (Phylaxia, Budapest) and 34 ga. needles (provided by Prof. D.G. Whittingham. Surrey, U.K.). Basically, the method described by Hogan et al., (1986) was followed in zygote, embryo recovery and evaluation using a disecting microscope. Blood samples were collected from treated and control animals. Blood samples were centrifuged and kept in a deep-freezer of -2OOC till assay for Vitamin A according t o the fluorometric method (Blaskovits et al., 1980) was conducted. The ovulation rate in tht. treated group was more than 9 % higher than those in the control group under no-ma1 ovulation rate or under superovulation. Number of U.S.
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